Spinning-in the ends of tubes



Oct. 3, 1950 E. A. BLAMPIN 2,524,420

SPINNING IN THE ENDS 0F TUBES Filed Sept. 20, 1947 2 Sheets-Sheet l Oct. 3, 1950 E. A. BLAMPIN 2,524,420

SPINNING IN THE ENDS 0F TUBES Filed Sept. 20. 1947 2 Sheets-Sheet 2 VENTOg.

Patented Oct. 3 1950 UNITED STATES PATENT OFFICE SPINNING-IN THE ENDS F TUBES Earle A. Blampin, Grand Island, N. Y. Application September 20, 1947, Serial No. 775,360

3 Claims.

This invention relates to improvements in methods and apparatus for closing or partly closing the ends of tubular metal members.

One of the objects of this invention is to provide method and apparatus for turning-in the ends of a tubular member by means of a spinning operation resulting from relative rotation of the tubular member and a die. A further object of this invention is to provide apparatus including a die having a partly conical recess into which the end of a tubular member is pressed with the axes of the tubular member and die at an angle to each other in such a manner that upon relative rotation of the tubular member and the die, the metal of the tube will be wiped toward the axis of the tube. Another object is to provide a method and apparatus of this type by means of which the metal of the tubular member when flanged-in toward the axis of the tube becomes heated by friction to a temperature sufficiently high to cause the end of the tube to be welded to form a tight closure on the end of the tube. Another object of this invention is to provide apparatus of this type in which the die comprises a plurality of rods of a metaloralloy capable of resisting high temperatures, and in which the rods are arranged so that the ends thereof which engage the tubes form portions of a conical recess. Other objects and advantages of this invention will appear from the following description and claims.

In the accompanying drawings:

Fig. 1 is a top plan view of an apparatus embodying this invention and showing the parts thereof mounted on a lathe.

Fig. 2 is a fragmentary longitudinal central section of a tube before the end thereof is turned-in;

Fig. 3 is a similar section showing the tube after the end thereof has been closed by means of the apparatus shown in Fig.1.

Fig. 4 is a view, partly in section, on an enlarged scale, of the die shown in Fig. 1.

Fig. 5 is a face view of a die of modified construction.

Fig. 6 is a section thereof, on line 6-45, Fig. 5

Fig. 7 is a fragmentary, sectional view of the die with a tube in operative relation thereto for spinning over the end of the tube, the section being taken approximately on the axis of the die.

Fig. 8 is a sectional view thereof, on line 8-8, Fig. 7.

Fig. 9 is a fragmentary sectional view similar to Fig. 8, but showing the tube farther advanced into the die.. i a

Fig. 10 is a sectional view thereof, on line lfllll, Fig. 9. 5 1

Fig. 11 is a fragmentary sectional view similar to Figs. 8 and 10, but showing the tube still far, ther advanced into the die.

Fig. 12 is a sectional view thereof, on line I2-I2, Fig.11.

Fig. 13 is a fragmentary sectional view similar to Figs. 8, l0 and 12, but showing the tube in final position with reference to the die. a

Fig. 14 is a sectional view thereof, on line M-I4, Fig. 13.

Fig. l5 is a view, partly in section, of a modi: fied apparatus by means of which. the end of a tube may be turned inwardly while the tube is held stationary by means of a die rotating about the tube. 1

In Fig. l, 8 represents the bed of a lathe on which apparatus embodying my invention may be mounted. 9 represents the lathe spindle having a collet ill by means of which a tube A to be operated upon may be clamped in place. It will be understood that the lathe spindle 9 andthe collet may be rotated by any suitable means (not shown), such as commonly employed in connec: tion with lathe headstocks, or the spindle and collet may be disconnected from its driving means so that it may be free to rotate in either direction. It is to be understood that while a lathe lends itself well for use in connection wit.h;my improved apparatus, yet it is not intendedto limit this invention for use in connection with lathes, since machines of other types for rotatablysupporting or for positively rotating the tubes, may be employed for use in connection with my improved apparatus.

. The turning or spinning in of the end of a tube or tubular member is eifected by means of a die having a circular or partly circular surface. or edge which is engaged by the tube while extending at an angle to the axis of the circular surface or edge of the die. In Fig. 4, I have shown by way of example one type of die l2 which may be used in connection with the turning-in of the ends of tubes, this die being made of a suitable hard material having alconical or frusto-conical recess I4 formed therein. The middle portion of the die may be provided with a hole l5, if desired, to receive any chips or scale which may be, removed from the tube during the turning-in operation, but this hole may be omitted, if found unnecessary. The die may be suitably secured in a die holder H5 in any suitable manner, the die holder having a stem or shaft I 1 about which the die holder may rotate, the axis of the stem or 3 shaft being concentric with the axis of the conical or partly conical recess 14.

In the use of this die, the tube to be operated upon is arranged relatively to the die with the axis of the tube extending at an angle to the axis of the conical recess in the die preferably in such a manner as shown in Figs. 1, '7, 9, 11 and 13. When the parts are in this relation to each other, the tube may have the end portion thereof spun or formed inwardly either by relative rotation of the die about the axis of the cone, while the tube is pressed into the die cavity and is free to rotate, or while the tube is driven to rotate about its axis. Also the end of the tube may be formed inwardly by leaving the die free torotate due to frictional contact with the tube. The direction of rotation of the tube and die about their axes is immaterial. The tube and die are pressed into contact in such manner that as the end of the tube is turned inwardly, it enters more deeply into the die recess, and the relative rotation of the tube and the die must be such that the die has a spinning or wiping action about the entire periphery of the end of the tube.

In the construction shown in Fig. 1, the shaft 11 of the die holder I6 is rotatably mounted in a bearing 18 arranged at an angle to the axis of the lathe spindle. In the particular construction illustrated, the shaft I"! may be rotated by means of a motor 20 mounted above the bearing !8 and the die and its shaft I1 may be rotated by the motor through the medium of one or more pulleys 2| mounted on the motor shaft connected by a belt with pulleys 21a. The motor and the bearing l8 are suitably mounted on a slide '22 arranged to slide lengthwise of the bed 8 of the lathe.

In the particular construction illustrated, the slide 22 with the motor mounted thereon is arranged to be yieldingly urged to the left in Fig. 1, while the end of the tube is being turned inwardly, and for this purpose, a cylinder 25 may be secured to the lathe bed 8, this cylinder having a piston connected with a piston rod 26, the outer end of which is suitably secured to a bracket 21 secured on the bearing bracket or other part of the slide 22. The cylinder has conduits 28 and 29 adjacent to the opposite ends thereof through which motive fluid, such for example as compressed air, may be admitted to the cylinder at either side of the piston. When a tube is secured to the lathe collet in correct relation to the die [2 and the collet is rotated, the motive fluid is admitted to the cylinder 25 so as to urge the piston to the left in Fig. l, to exert pressure of the die against the end of the tube A, thuscausing the tube A, as the end thereof is spun inwardly, to enter more deeply into the die cavity. During this operation, the die i2 may be permitted to rotate due to frictional contact with the tube A, or the die may be rotated by means of the motor 20 through the pulleys 2| and. 2la and the belt connection with the shaft ll as described. I have found that when operating on tubes with relatively thin side walls, it 'is best to rotate the die during the rotation of the tube A and when operating on small tubes with relatively heavy side walls, the die may be left free to be rotated bythe tube. If the tubes are quite thin and considerable heat is required, the die may be rotated in a direction opposite to the direction of rotation of the tube. If less heat is required, the direction of rotation of the die and the tube may be the same.

In the operation of the method and mechanism described, a die with a conical recess is employed for the reason that any section of the cone parallel to its base is a circle, and when the end of the tube is spun inwardly to form a substantially hemispherical end thereon, it is noted that the tube contacts the die only along a circular line or narrow band thereon, this circle lying in the section 88 in Fig. '7. Consequently, when the end of the tube is first inserted and pressed into the die recess, the tube will engage only a relatively small part of the circle or circular band of the die, for example, the lower part thereof as shown in Fig. 8, thus producing a relatively small, inwardly extending flange 30 on the tube. As the tube enters the die cavity to a greater extent, due to pressure of the die toward the tube as shown in Fig. 1, or due to pressing the tube into the die cavity, a larger flange 3! will be formed on the tube as clearly shown in Figs. 9 and 10, and the turned-in portion of the tube will engage a greater portion of the circle or circular band within the die with which the tube contacts, as shown in Fig. 10. As the tube enters farther into the die, a larger iinturned portion 32 is formed thereon which, in turn, engages with a larger portion of the circle as shown in Fig. 12. Upon further entry of the tube into the die cavity as shown in Figs. 13 and 14, the end of the tube will be entirely closed and at this time, the end of the tube will contact with the entire circle of contact within the die cavity [4 as shown in Fig. 14 and the axial portion of the tube will be welded 'to form a tight closure at the end of the tube.

A great deal of friction results from the turning-in of the end of the tube by means of the die in the manner described, and this friction results in the heating of the tube. The amount of friction may be controlled 'by the relative speeds of rotation of the tube and die and by the pressure with which the tube and die .are pressed into contact. Consequently, when the tube and die are rotated in opposite directions, the maximum heating of the end of the tube will take place. This fact can be utilized to good advantage in operating on tubes or cylinders having walls of different thicknesses and strength. For example, when operating on a relatively thin tube of brass or other metal of less strength than steel, heavy pressures cannot be used for pressing the tube and die into contact and in such cases, the necessary friction to heat the end of the tube sufficiently for turning-in the end and for welding the end is produced by rotating the tube and die in opposite directions. When operating on relatively heavy walled steel tubes, the die in Fig. 1 may be left free to rotate without positively driving the same, since the die will be driven frictionally by the tube. It is also possible to accomplish the desired result in some cases by holding the die against rotation but this results in uneven wear on the die. In most cases, no preheating of the tubes is necessary, the friction supplying all the heat required for softening the tube for turning-in and for welding, but in the case of large tubes or cylinders, I prefer to preheat the ends of the tubes before spinning the same in my apparatus, for the purpose of reducing the time required for the operation and to reduce the wear on the dies. The process is preferably carried on with sufiicient pressure and speed of rotation so that the spinning of the end takes place quickly so that the end of the tube may be welded before much heat is conducted from the end of the tube to other parts thereof.

The portion of. the end of the tube nearest to the longitudinal axis thereof becomes heated to theh greatest extent, and in actual use of the apparatus, it is found that this axial portion of the tube becomes heated to a white heat. Conse quently, when the tube is inthe position shown in Figs. '13 and 14 with reference to the die, the metal at the axial portion of the tube becomes so hot that a perfect weld is formed, so that a gas-tight seal can be formed at the end of the tube by means of the method and apparatus described. It is, of course, not necessary to continue the spinning of the end of the tube to such an extent as shown in Fig. 13, unless a tight closure at the end of the tube is desired. In many cases, only a flanging-in of the tube is required, in which case, the feeding of the tube and die relatively to each other may be stopped at any time when the desired amount of flanging-in has been effected. Consequently, by means of the apparatus and the method described, tubes can also be formed with relatively small openings in the ends thereof.

In the constructions shown, a 90 degree conical recess in the die is provided, this being desired when a substantially hemispherical end is to be formed on the tube. When this is desired, the tube is preferably arranged at an angle of about degrees to the axis of the die, but it has been found that better results are obtained if theangle of the tube relatively to the die is slightly less than 45 degrees as shown in Figs. 7, 9, 11 and 13, so that the tube willcontact only in the circular band lying in the section 8 8 of Fig; 7. By providing an angle of slightly lessthan 45 degrees, such for example as 42 del grees or 43 degrees or slightly less, the cutting or grooving of the tube by the outer edge of the die cavity is avoided.

As will be clearly seen by examination of Figs. 7, 9, 11 and 13, the spinning-in is effected by a Wiping action of the die on the metal of the tube. For example, as the die rotates relatively to the tube, portions'of the die, in rotating, will rub the metal of the tube from the base of the semi-circular end to the apex thereof on one side of the axis of the die, while a corresponding rubbing of metal from the apex toward the base of the hemispherical end will result at the other side of the axis of the die. In many cases, it is desirable that the metal of the tube be rubbed by the die only from the base of the hemisphere toward the apex thereof, and when this is desired, the tube is supported in such a manner relatively to the die that the axis of the tube will not intersect the axis of the die, but will lie slightly at one side thereof, namely, at the side thereof at which the die wipes or rubs the metal from the base of the hemisphere to the apex thereof. When the axis of the tube is thus located at the correct side of the axis of the die, very quick and effective wiping or spinning-in of the end of the tube results, and the metal of the tube will, to a certain extent, be accumulated in the axial portion of the end of the tube, so that the end of the tube will be of greater thickness than the side walls of the tube, and in some instances, an accumulation of metal at the axial portion of the tube will be noted as shown at 33 in Fig. 14.

It is not necessary to have the cavity in the die in the form of a 90 degree cone as shown in the drawings. However, if the substantially perfect hemispherical end is desired on the end of the tube with the base of the hemisphere of the Same diameter have illustrated a die a 90 degree cone must be used with the tube arranged at an angle, as close to 45 degrees to the axis of the conical recess in the die as possible. If the angle of the conical recess in the die is greater than 90 degrees, the shape of the spun-in end of the tube will be slightly different and will have a substantially frusto-conical portion adjoining thecylindrical portion of the tube and a hemispherical portion adjoining the reduced end of the frusto-conical portion. If the frusto-conical recess in the die has an angle of somewhat less than 90 degrees, then the tube will have to be arranged at a correspondingly smaller angle to the axis of the die, and the closed end of the tube will be somewhat more pointed than a hemisphere.

While it will be obvious from inspection of Figs. 7 to 14 that only a single circle in the die is necessary to effect the desired spinning of the end of the tube, and that, consequently, a die having only a circular edge portion for spinning the end of the tube will accomplish the desired results, a die having tube engaging surfaces arranged on the surface of a cone is preferred,

since it facilitates the proper feeding of the tube to the die, and furthermore, such die will operate successfully on tubes varying somewhat in size. i i

It is not necessary that the die be made of a single piece of metal with a conical recess therein, since a die which merely has contact points to engage the tube and which are arranged to form portions of a conical recess in the tube may be employed. For example, in Figs. 5 and 6, I

holder 35 which has a plurality of holes 36 therein, in which rods 31 are arranged. The die holder need not be made of hard steel or alloy, and the rods 3'! may be made of tool steel, or if desired, these rods may have the outer ends thereof provided with disks 38 of an alloy which is extremely hard and capable of withstanding high temperatures, such for example as any of the well-known sintered carbides. This last mentioned construction is particularly desirable when operating on stainless steel tubes or ontubes of other extremely hard alloys.

Three or more of these rods spaced symmetrically about the axis of rotation of the die, four being shown in Figs. 5 and 6. The rods may be held in their outer positions bymeans of studs 39 extending through threaded holes in the die holder and engaging the rods 31, and if desired, lock nuts 40 may be provided for holding the studs in adjusted positions. The adjacent ends of these rods 35, consequently, havejportions thereof which form portions of a conical surface within the die holder and with which the ends of tubes to be turned-in may engage. Dies of this type are desirable because they are easy to maintain in operative condition, since wear on the inner ends of the rods can readily as the diameter of the tube. then be rectified by removing the rods from the die holder and grinding down the tube engaging ends thereof perpendicular to theiraxes.

In Fig. 15, I have illustrated a modified form of my apparatus in which the tube A may be held in fixed position throughout the spinning process and the die l2 and die holder I6 are rotatably mounted on a revolving head 42 mounted on a shaft 43, the axis of which coincides with the axis of the tube A. The die holder l6 has its stem 44 rotatably mounted in a recess 46 in the head 42, the recess being in the form of a cylindrical hole arranged at an angle to the axis may be employed,

of rotation of the shaft 43. For example, if the tube is to be pro- Vided with a substantially hemispherical closed end, the axis of the cylindrical recess 46 should be arranged at an angle of 45 degrees or slightly less to the axis of rotation of the shaft 43. The stem 44 may be journalled in ball bearings 41 in the recess 4%.

As a result of this construction, if the shaft 43 is rotated, it will b 'noted that the die i2 will rotate about the tube A. The tube and die are pressed toward each other, either by moving the tube toward the die or by moving th shaft 43 toward the tube. The operation resulting from the use of this apparatus is the same as that produced by the apparatus shown in Fig. 1, except that with the apparatus shown in Fig. 15, the tube A may be held against rotation. The die it in Fig. 15 rotates bodily about the axis of the shaft 43 and is free to rotate about its own axis because of the rotatable mounting of the shaft or stem 44 in the bearings formed in the head 42.

It will b evident that when the die has a 90 degree conical cavity or the rods 31 of the die shown in Figs. 5 and 6 are arranged so that portions of the tube engaging ends of the rods lie in portions of a 90 degree cone and the tube is arranged with its axis at approximately 45 degrees to the axis of the conical cavity, the circular sec tion of the die engaged by the axial portion of the tube as shown in Fig. 13, will wipe across the axial portion of the end of the tube in a direction substantially perpendicular to the axis of the tube, thus ensuring a tight closure of the end of the tube. By means of my apparatus andmethod described, tubes can readily have their ends flangedin, or the ends of the tubes may be tightly closed by welding. In the case of smaller tubes or thinwalled tubes, all of the heat necessary for softening the walls of the tubes and for turning the same in and for closing the end by welding is derived entirely from the frictional engagement of the tube and the die. Consequently, by means of this method and apparatus, tubes can be very quickly closed or turned-in without the use of any external welding heat. Larger tubes can also have their ends turned inwardly or closed by welding, merely by use of the die itself, but generally, it is more efficient to heat the ends of the tubes preliminarily for the purpose of saving wear on the die. In the case of larger tubes, however, the temperature to which the ends of the tubes are raised need not be high enough to effect satisfactory welding of the same, the additional heat necessary for welding being supplied by the frictional engagement of the tube and the die.

It will be understood, of course, that the drawings merely illustrate certain embodiments of this 8 I invention for the purpose of explaining the nature of this invention, but it will be clear that various changes may be made by those'skilled in the art without departing from the principle and scope of this invention as expressed in the claims.

I claim as my invention:

1. Apparatus for spinning an end of a tube inwardly toward the axis thereof, including a'die having a cavity with tube engaging portions thereof arranged on the surface of a substantially degree cone, means for supporting a tube with its axis arranged at an angle of approximately 45 degrees to the axis of said. cone, means for pressing the end of said tube and said die into contact while maintaining said angular relation of said tube and die, and means for producing relative axial rotation of said tube and die while in said angular relation to each other.

2. Apparatus according to claim 1, in which the angular relation of the tube to the axis of the die is slightly less than 45 degrees and in which the axis of the tube lies slightly to one side of the axis of the cone.

3. Apparatus for spinning an end of a tube inwardly toward the axis thereof, including means for holding said tube with its axis in fixed relation to other parts of the apparatus, a die having a cavity with tube engaging portions thereof arranged on the surface of a cone, a revolving head rotatable about an axis in alignment with the axis of said tube, means on said head for rotatably mounting said die with the axis of said cone extending in angular relation to the axis of said tube, means for revolving said head to cause said die to move about the end of said tube, and means for pressing said tubeand die into contact with each other, said tube being arranged relatively to said die with the outer surface of the side wall of the tube extending substantially tangent to and within said cone.

EARLE A. BLAMPIN.

REFERENCES CITED The following references are of record in the file of this patent:

, UNITED STATES PATENTS Number Paucek Sept. 14, 

